Electrochemical devices, such as batteries, supercapacitors, etc., which may be prepared from nanoscopic electrically conductive carbon materials, and optionally electrochemically active materials. Also, methods for preparing such electrochemical devices, including components, elements, etc., of such devices by using three-dimensional (3D) printing, fused deposition modeling (FDM), selective laser sintering (SLS), etc., techniques.

This electricity storage device which is configured to contain an ionic liquid represented by formula (1) in, for example, an electrolyte or an electrode has the advantage of being usable in a low-temperature environment in spite of the ionic liquid contained therein.

##STR00001##

(In the formula, each of R.sup.1 and R.sup.2 independently represents an alkyl group having 1-5 carbon atoms; and n represents 1 or 2.)

This electricity storage device which is configured to contain an ionic liquid represented by formula (1) in, for example, an electrolyte or an electrode has the advantage of being usable in a low-temperature environment in spite of the ionic liquid contained therein.

##STR00001##

(In the formula, each of R.sup.1 and R.sup.2 independently represents an alkyl group having 1-5 carbon atoms; and n represents 1 or 2.)

An energy storage apparatus suitable for mounting on a printed circuit board using a solder reflow process is disclosed. In some embodiments, the apparatus includes: a sealed housing body (e.g., a lower body with a lid attached thereto) including a positive internal contact and a negative internal contact (e.g., metallic contact pads) disposed within the body and each respectively in electrical communication with a positive external contact and a negative external contact. Each of the external contacts provide electrical communication to the exterior of the body, and may be disposed on an external surface of the body. An electric double layer capacitor (EDLC) (also referred to herein as an “ultracapacitor” or “supercapacitor”) energy storage cell is disposed within a cavity in the body including a stack of alternating electrode layers and electrically insulating separator layers. An electrolyte is disposed within the cavity and wets the electrode layers. A positive lead electrically connects a first group of one or more of the electrode layers to the positive internal contact; and a negative lead electrically connects a second group of one or more of the electrode layers to the negative internal contact.

An energy storage apparatus suitable for mounting on a printed circuit board using a solder reflow process is disclosed. In some embodiments, the apparatus includes: a sealed housing body (e.g., a lower body with a lid attached thereto) including a positive internal contact and a negative internal contact (e.g., metallic contact pads) disposed within the body and each respectively in electrical communication with a positive external contact and a negative external contact. Each of the external contacts provide electrical communication to the exterior of the body, and may be disposed on an external surface of the body. An electric double layer capacitor (EDLC) (also referred to herein as an “ultracapacitor” or “supercapacitor”) energy storage cell is disposed within a cavity in the body including a stack of alternating electrode layers and electrically insulating separator layers. An electrolyte is disposed within the cavity and wets the electrode layers. A positive lead electrically connects a first group of one or more of the electrode layers to the positive internal contact; and a negative lead electrically connects a second group of one or more of the electrode layers to the negative internal contact.

A lithium ion capacitor has an electrolytic solution that contains: 100 parts by volume of a solvent containing 20 to 50 parts by volume of propylene carbonate, 10 to 35 parts by volume of dimethyl carbonate, and 15 to 70 parts by volume of ethyl methyl carbonate; and lithium bis(fluorosulfonyl)imide, as an electrolyte. The lithium ion capacitor can maintain its initial high capacitance and low internal resistance, while also undergoing minimal characteristics changes in a low-temperature environment, even after exposure to a high-temperature, high-voltage environment.

A lithium ion capacitor has an electrolytic solution that contains: an electrolyte which is a mixture of LiFSI and LiBF.sub.4, where the mol ratio of LiFSI to LiBF.sub.4 is in a range of 90/10 to 30/70; a solvent that contains at least one type of cyclic or chained carbonate compound; and a film-forming agent; wherein the concentration of electrolyte in the electrolytic solution is in a range of 1.2 to 1.8 mol/L. The lithium ion capacitor can maintain its initial high capacitance and low internal resistance, while also undergoing minimal characteristics changes after exposure to a high-temperature, high-voltage environment.

An aspect of the present invention is a nonaqueous electrolyte energy storage device including: a positive electrode including a positive active material layer of 5 mAh/cm.sup.2 or more in capacity density per unit area; a negative electrode including metallic lithium; and a nonaqueous electrolyte including an ionic liquid and a fluorinated ether.

In one embodiment, the present invention relates to an electric device, comprising an electrolyte comprising a solvent; a first quaternary ammonium or phosphonium salt; and a second quaternary ammonium or phosphonium salt, containing an ammonium group having a general formula [NR.sup.1R.sup.2R.sup.3R.sup.4].sup.+, or a phosphonium group having a general formula [PR.sup.1R.sup.2R.sup.3R.sup.4].sup.+, wherein R.sup.1═R.sup.2, R.sup.3═R.sup.4, R.sup.2≠R.sup.3, and each R.sup.1, R.sup.2, R.sup.3 and R.sup.4 independently is a branched or unbranched alkyl group containing from 1 to about 20 carbon atoms, and in which each salt comprises an anion, and wherein the first and second ammonium or phosphonium are not the same. In another embodiment, the present invention relates to the electrolyte.

In one embodiment, the present invention relates to an electric device, comprising an electrolyte comprising a solvent; a first quaternary ammonium or phosphonium salt; and a second quaternary ammonium or phosphonium salt, containing an ammonium group having a general formula [NR.sup.1R.sup.2R.sup.3R.sup.4].sup.+, or a phosphonium group having a general formula [PR.sup.1R.sup.2R.sup.3R.sup.4].sup.+, wherein R.sup.1═R.sup.2, R.sup.3═R.sup.4, R.sup.2≠R.sup.3, and each R.sup.1, R.sup.2, R.sup.3 and R.sup.4 independently is a branched or unbranched alkyl group containing from 1 to about 20 carbon atoms, and in which each salt comprises an anion, and wherein the first and second ammonium or phosphonium are not the same. In another embodiment, the present invention relates to the electrolyte.